Thomas, The size of the pre-fetch stripe used by disk arrays is the same if you read one block at time or one CYL at a time, so the potential to create sibling is the same for OPT(1) and OPT(4).
OPT(1) will slightly increase channel and port MP usage because of the increased command processing overhead. Unless you have some sort of marginal channel configuration I would subscribe to the "bigger is better" rule - especially on FICON. Ron > -----Original Message----- > From: IBM Mainframe Discussion List [mailto:[EMAIL PROTECTED] On > Behalf Of Thomas H Puddicombe > Sent: Tuesday, 13 June 2006 11:09 PM > To: [email protected] > Subject: Re: DFSMSdss Performance Question > > The performance of a single DF/DSS job using OPT(4) will be better than > OPT(1). "N" concurrently executing DF/DSS jobs, each specifying OPT(4) > may not be a "good thing" for overall performance - depending on channel > configuration, make and model of I/O devices, etc. - for sufficently large > values of "N". > > Performance quant's standard answer #1: "It depends" > > ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [EMAIL PROTECTED] with the message: GET IBM-MAIN INFO Search the archives at http://bama.ua.edu/archives/ibm-main.html
